Method of designing gear using CAD system, and gear

Abstract

A method of designing a gear in which a tooth trace of the tooth flank, which is to be engaged with another mating tooth flank, is curved with respect to an axial direction of the body of the gear. The mating tooth flank of the mating gear is designed in such a manner that a desired tooth contact can be achieved. Accordingly, sufficient design precision can be attained. Furthermore, stress at the tooth flanks can be controlled when the gears are engaged with each other, thereby leading to high durability of the gears.

1. A pair of gears, each of which has a tooth to be engaged with another mating tooth, wherein
 one tooth flank ( 4   a ) of one gear (W 1   a ) is designed using a CAD system by continuously transitioning a tooth trace consisting of a circular arc (R 1 ), from a tooth root of the gear to a tooth tip thereof, and 
 a mating tooth flank ( 3   b ) of a mating gear (W 1   b ), which is to come in contact with the one tooth flank ( 4   a ), is designed using a CAD system by continuously transitioning a tooth trace curve (R 2 ) consisting of two circular arcs ( 61 ,  63 ) and of a connecting curve ( 65 ) connecting the two circular arcs ( 61 ,  63 ), from a tooth root of the mating gear to a tooth tip thereof, each circular arc ( 61 ,  63 ) being formed by a circle ( 62 ,  64 ), the circle ( 62 ,  64 ) being generated, for each of two contact points at which a hypothetical tooth trace ( 54 ) contacts with a mating contact curve (R 4 ), in such a manner that the circle ( 62 ,  64 ) comes in contact with a circular arc being the corresponding hypothetical tooth trace ( 54 ) and has a diameter smaller than that of the circular arc being the corresponding hypothetical tooth trace ( 54 ). 
 
     
     
       2. A pair of gears according to  claim 1 , wherein
 the connecting curve ( 65 ) is formed by an ellipse that comes in contact with the two circular arcs ( 61 ,  63 ) at connecting points of each other.